Force per unit area.

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1answer
66 views

Velocity of a liquid jet, coming out of a container

Think of a container which has a hole beneath it. And we have filled the container in height $h$ with a liquid of density $\rho$ and cross section of the hole $a$. (look at the pic) Then what is the ...
0
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1answer
40 views

Perfect vacuum in experiment [closed]

When conducting experiments to determine the speed of light in a perfect vacuum does that vacuum(?) replicate outer space?
1
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0answers
36 views

Gas chamber problem [closed]

Consider a rectangular isolated(non-conducting) chamber as shown below. The chamber is divided into three compartments. The wall separating A and B has negligible mass, no friction and is conducting, ...
0
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1answer
128 views

How to calculate air flow from a pressurized tank?

I am writing an app that deals with simulated air brakes, and I need to simulate the release of air from one container of a given pressure into another container of a lower pressure. It doesn't have ...
0
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1answer
103 views

How to find gauge pressure in pipe

If I have a pipe for which I know the height and velocity of the fluid at the left and right end, and I am asked to find the gauge pressure at the right end, how would I go about doing this if the ...
1
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1answer
126 views

Can a hose filled with water go up if there is not a lot of pressure?

This might be more a general knowledge-type question or physics basics (or maybe not even physics) if so, I apologize and never took a physics class (my school never offered it), so I am not really ...
3
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0answers
63 views

sound propagation at low pressure

I am curious about the properties of sound at low atmospheric pressure. Not the speed of sound, I want to know how lower pressure will affect the distance sound will carry and the frequency range. For ...
1
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0answers
39 views

pressure of water in all directions [duplicate]

As far as I understand, pressure acts downwards on a surface of a body in water because pressure $P$ is given by $$ P = \frac{F}{A} = \frac{m \, g}{A} $$ where $F$ is the gravitational force on the ...
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1answer
53 views

Difference of water pressure

We know that $P = \rho gh$, so is it true that water pressure at 2nd floor will be higher than water pressure at 9th floor of a 12 story building?
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1answer
59 views

Liquid phase is a highly compressed gaseous phase

$\mathbf{Q:}$ While teaching "Real Gases", my professor remarked last day that "Liquid phase is a highly compressed gaseous phase." But he did not explain the reason behind it and left it as food for ...
1
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1answer
20 views

Injected gas versus pressure rise

Very simple concept for some, but quite honestly I’m striving to grasp: Premises: You have a $20 \text{ m}^3$ pressure vessel. You start filling it with gas. You see a rise in the gauge pressure ...
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2answers
76 views

Pressure at ground level and at sea level

1atm = 101325pa 1bar = 100000 pa 1atm = 1.013 bar 1bar = 0.987atm From wiki: The bar is a metric (but not SI) unit of pressure exactly equal to 100000 Pa.[1] It is about equal to the atmospheric ...
0
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1answer
69 views

How does speed of gas molecules change with pressure? [closed]

A thought experiment. I have a box of fixed dimensions, inside this box I have molecules of $H_2$ at constant temperature. I'll be gradually increasing pressure inside the box and the temperature ...
34
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4answers
5k views

What is the energy source if a tall water tank is used to transfer floating objects upwards instead of cables with motors?

Suppose I want to transport some logs from the ground to the roof of a tower. Originally I can use a lift, or some cables, or even move the logs upwards manually; then the energy is converted to the ...
1
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2answers
52 views

why is pressure more convenient than force while dealing with fluids? [duplicate]

If two equal and opposite forces act on a surface, can I say the pressure is zero because the net force is zero? How can pressure be non directional when force as a direction? How can the pressure of ...
-1
votes
3answers
85 views

Velocity of water from a certain depth

I was curious to know does water come out of a certain depth when there is a difference in pressure, and also if it does come out of a certain depth, at what velocity does it travel at? So, ...
0
votes
1answer
24 views

Pressure Change in Supersonic Wind Tunnel [closed]

As far as I know, the total pressure changes across a shock wave. How is this possible if you are in the atmosphere and atmospheric pressure isn't changing? Is energy lost due to entropy in ...
0
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1answer
55 views

Rate of applied force versus material failure?

Question: Does the rate at which a force is applied to an object determine the maximum force reached that mechanically fails the object? If so, what are the concepts that need to be understood to ...
1
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1answer
58 views

Effect of radiation pressure on Earths orbit in large timescales

I have seen some posts concerning the radiation pressure exerted by the Sun on Earths surface (Force on Earth due to Sun's radiation pressure). Though it is fairly small may it have a considerable ...
0
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1answer
52 views

Perfect fluid and EM tensor in rest frame

I see that we use perfect fluid which is characterized by a energy density and isotropic pressure for general forms of matter. When guessing the values of energy momentum tensor indices we can use ...
0
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1answer
103 views

How does a pop pop boat work?

I have been reading about the pop pop boat on wikipedea. What I don't understand is after the hot water is ejected the vacuume gets created, so when the same amount of water will be sucked in the boat ...
0
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4answers
143 views

Velocity of a leak in a closed water tank

Bernoulli's equation states $P_1+{1\over2}\rho v_1^2+\rho g h_1 = P_2+{1\over2}\rho v_2^2+\rho g h_2$ In a classic "water tank with an open top and a leak" scenario, "point 1" is the surface water ...
1
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1answer
40 views

Do liquids creep from cold to hot like gases?

Consider the U-tube water experiment below with the left red block at 10C and the right red block at 90C. I think the right level will become about 3% higher than the left level simply because hotter ...
0
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1answer
35 views

Hydrostatic pressure in a vase at different depths

I am building a water level sensing device on the base of Arduino. The sensor is the eTape by Milontech. The resistance changes almost linearly with depth as the sensor is immersed in liquid (...
3
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2answers
181 views

Pressure change when closing valve inside a column of water

Main question: If you have a column of fluid with a valve as shown on the drawing, what happens to the pressure at the point p when moving from state A to state B ...
0
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1answer
297 views

Pressure exerted by a liquid on walls of a container (quantitative)

I want to calculate the total pressure exerted by a liquid of density ρ on the walls of a container, say a cylinder, for convenience. $$P = hρg$$ Therefore integrating from $0$ to $h\; ,$ we get : ...
5
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4answers
247 views

Why the round trip instead collision time?

From Newton's second law, the $\Delta t$ is defined as the collision time, but why in this case, it can be assumed to be the value of time between successive collisions on 1 wall? If I have an ...
0
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0answers
96 views

Pressure inside tank while discharging water

I have two tanks, one initially fully filled with water (large tank) and the other one (smaller) is empty and has low pressure (say 0.5 bar) and the two tanks are connected from the bottom with pipe ...
0
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2answers
36 views

Nature of Pressure

Pressure is defined as force per unit area. Therefore, pressure = force divided by area. Since force and area are both vectors, how can we perform this division without violating the rule of vectors? ...
0
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1answer
134 views

Why is it not possible to use the ideal gas law to determine if the pressure changed in this situation?

I was given this question for my homework: A cylinder with a valve at the bottom is filled with an ideal gas. The vale is now opened and some of the gas escapes slowly. The valve is then closed, ...
0
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2answers
64 views

How much Oxygen is in ζ-phase metallic Oxygen?

I am playing with a sci-fi idea of Oxygen storage for breathing. I wonder how do some compressed forms of Oxygen compare to human-breath-Oxygen (room temperature, room pressure) in terms of density. ...
1
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0answers
11 views

Capillary bridge force function given volume and distance

Given two surfaces and a fluidic glue with sufficient adhesion, what is the force provided by the capillary bridge provided the cohesive properties of the glue, volume, and distance between the ...
-1
votes
1answer
51 views

Managing nuclear waste [closed]

Suppose you are trying to dispose of used uranium fuel rods. Once they are cooled and contained in zirconium pods, how would one try and send those pods to the earths core? This is all hypothetical. ...
1
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1answer
28 views

Compute affect of a shower on density altitude

As a pilot I have a basic understanding of density altitude, how temperature affects the effective air pressure: I noticed recently that I have difficulty breathing when I take a shower in Santa ...
0
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1answer
62 views

$\rho g h$ and shape of container inconsistency?

The Scenario Suppose I have a cylindrical beaker and a conical flask (which cross-sectional area is bigger at the bottom), each located on an identical digital weight scale. Both of them have the ...
1
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2answers
51 views

Volume integral of pressure interpretation

If you have a fluid with with pressure field $p$ what is the physical significance of the the volume integral of the pressure $\int_V p dV$?
0
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1answer
50 views

Pressure,Pascals Law [duplicate]

Lets say that i have 2 different types of containers, one cuboidal and another one conical. and lets say both these are massless and fully contain water. **1.**In the cuboidal one the pressure ...
0
votes
1answer
350 views

Calculating flow rate of a syringe

I wanted to know how would I go about calculating the flow rate of a syringe with a metal tip that is dispensing water using a pressurized air. I have had a look on internet about this and on this ...
0
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1answer
66 views

why don't we consider atmospheric pressure or weight of liquid while deriving the equation of thrust in a fluid?

More specifically , when we try and prove that up thrust experienced by an liquid column inside the liquid is equal to the weight of the liquid column , I have seen it being derived like this: thrust ...
0
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3answers
91 views

If Gravity acts on the particles in the gas, why don't they accumulate on the lower surface and fall down?

A quantity of gas is enclosed in a metal cylinder fitted with a piston. There are very many gas molecules.The cylinder walls are thermally conducting. Now, the question...
1
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1answer
90 views

Bernoulli Principle and pressure function

I have read in several places now that for compressible flow the Bernoulli equation $$ \frac {v^2}{2}+ P\ + \Psi = \text{constant}$$ requires: $$P=\int {dp\over \rho(p)} $$ But I don't get ...
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0answers
60 views

Which property do the word Pressure refer to in General Theory of Relativity?

In this course by MIT Alan Guth while delivering the lecture stated " Both Pressure and Energy densities can produce gravitational fields. Negative pressure creates repulsive gravity and positive ...
3
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0answers
64 views

Bottle cap burst phenomenon [closed]

There is a trick you can do with a simple plastic water bottle: After putting the cap on as tight as you can, you twist the body of the bottle a few times so that it compresses the air in the bottle. ...
0
votes
1answer
47 views

how is the state parameter determined?

For radiation, dark energy and dust the pressure and energy density are related, respectively, by: $p=\frac{1}{3}\rho$ $p=-\rho$ $p=0$ My question is why? How does one show that this is how ...
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0answers
88 views

Air flow through a tube

During a discussion, a friend explained to me that the volume of air flowing through a tube could be increased up to the point where the air reached supersonic velocity. Presumably the pressure ...
0
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2answers
61 views

Pressure generated by a molecule inside an enclosure

I want to find the pressure generated by a molecule of mass $m$ and speed $v$ that is alone in an enclosure having the volume $V$. I wander if I can use the relation: $PV=mv^2/2$
0
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1answer
128 views

Methane under pressure [closed]

A tank is filled with liquid methane. Then it is closed. It sits in an infinite room at STP (standard temperature and pressure). (Initial temperature is not important; assume density of liquid ...
0
votes
1answer
30 views

Relative magnitudes of pressure gradient force and Coriolis force at midlatitudes

In the midlatitudes, both Coriolis and pressure gradient forces are present in the atmosphere. Can a statement be made about which one of the two forces is bigger in this region?
1
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2answers
798 views

Why is pressure an intensive property? [duplicate]

My teacher explained to me that we volume is an extensive property because it is additive in nature. But he also told us that pressure is an intensive property. Now according to the gas law equation $...
2
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8answers
171 views

Visualising gas temperature and gas pressure

Gas pressure is created when gas molecules collide with the wall of the container creating a force. Gas temperature is a measure of how fast the molecules are moving / vibrating. However, they both ...